Method for the manufacture of stuffing box packings



R. RADKE Nov. 24, 1964 METHOD FOR THE MANUFACTURE OF STUFFING BOXPACKINGS Filed Aug. 18, 1958 PREPAREA MlXTUREOF FIBERS/4NDLUBRKCATINGSUUDS ENVELOP FIBERS WlTH LUBRICATINGSOUDS FORM PAPER-LIKEFOILS DRY FOILS AND DEVIL INTO ENVELOPE!) FIBERS SPIN INTO A ROVlNG MAKESTUFFING BOX PACKING INVENTOR RudolfRadife BY /6W d 5 ATTORNEYS UnitedStates Patent 3,157,583 METHOD FQR THE MANUFAtIIURE 9F STUEFRNG BGXPACKlNGS Rudolf Baillie, 53 Schwalbenschwanz,Frankfurt am l t lain,Eschersheim, Qerinany Filed 18, 195 3, Ser. No. 755,456 '7 Claims.57-464) The present invention relates to a method for the production ofstuffing box packings and to stufiin box packings manufactured accordingto this method.

In general, stufiing box packings are made of fibers in combination withsolids having lubricating properties, and preferably also with bondingagents and with lubricants having a consistency which varies between theliquid and the semi-solid, such as waxes, fats and oils.

It has been suggested to manufacture stuffing box packings of the abovetype by spinning fibrous materials, such as abestos, into yarns andcoiling these yarns into reels, preferably in such a manner that theyarn windings of each separate layer are crossed with windings of thepreceding separate layer on the reel. These reels are then impregnatedwith the bonding agent, e.g. with natural or synthetic rubber, and asolid lubricant, e.g. graphite, is applied.

It has also been suggested to wind sleeve-shaped stufiing-bo-x packingsfrom a paper-like fibrous sheet or fiber fleece and then apply the solidlubricant to the same after impregnation thereof, preferably with abonding agent such as a glue or rubber solution.

The graphited sleeves are pressed in a tool to shorten the height. Thedie in the tool has a smooth inner surface and a smooth outer surfacewhich form smooth surfaces on the stuffing box packing which is pressedagainst the inner and outer surfaces of the die. The stufiing boxpacking is made firm by the pressing. Due to the previous graphiting thewhole surface is thereby coated with a thin film of graphite.

Such packings, which generally have a base of glued paper, are notparticularly resistant against steam or water and other liquids.

The thin film of graphite on the surface wears 0E after a relativelyshort time, and the exposed dry fibers will then cause very considerablefriction.

For these reasons the useful life of such packings is often very shortand they are of poor quality.

According to other methods, thin plastic or rubber bonded fibrous foilscontaining some added graphite have been manufactured on calenders. Butfor technical reasons in the production thereof the proportion ofgraphite should in general not exceed 28% and in no case 50%. Rolledstuffing box packings made in this manner are rather hard and do notpossess good sliding properties due to the comparatively low graphitecontent.

Finally, stufiing box packings are known which are plaited from threadssuch as artificial silk, or made from fabrics woven of such threads. Theartifical silk threads are produced by mixing colloidal graphite into aviscose solution or into a melt of the material which is to be drawninto yarn; the graphite is then forced out of the spinning nozzletogether with the material. Thus the threads of this type which weredischarged from the nozzle into the precipitation bath or were formedwhen the melt was setting, consisted of a uniform mixture of artificialsilk and of graphite finely distributed throughout each fiber. Nowalthough these graphite fibers, when used as components of stuffing boxpackings, have a certain lubricant effect, they are still veryimperfect, since the amount of graphite is too small and the graphite isnot present predominately on the outside of the fibers, and also not inthe form of minute flakes. It has also Hce been found that theimpregnation of all stuffing box packings known so far, whether theyconsist of yarns, woven, knitted or plaited textile fabrics, or ofpaper-like foils or fleeces deteriorated rapidly, since in thesematerials the graphite is present merely on the surface of the threadsor foils but not inside thereof.

The novel feature of the present method for the manufacture of stufiingbox packings consisting of fibrous yarns and lubricating solids is theapplication of the solid lubricant to the fibers used in the manufactureof the yarn such that every single fiber is completely envelopedthereby. These fibers are then spun into yarns and the packing ismanufactured in the usual manner preferably by ordinary textile process.

This method can be based on fibers of many different types, i.e. both onorganic fibers such as cotton, wool, silk, artifi ial silk,polytetratluorethylene, polyamide, etc., and on inorganic fibers such asasbestos, glass, quartz, slag and mineral wool etc.

The lubricant used is primarily graphite; but other lubricant additivesin powder form, such as mica, talc, molybdenum disulphide and the likecan also be used, also certain metal powders-such as lead, copper, tin,aluminum and zinc.

The method is performed by adding the lubricating solids, e.g. graphite,during the processing of the individual fibers such that before thespinning of a yarn the fibers are completely enveloped by the lubricant.The graphite or other solids will therefore actually be added to thefibrous materials not later than on the card.

A bonding agent is in most cases used at the same time. Various types ofsuch agents can be used, e.g. organic or inorganic adhesives.Particularly suitable are natural and synthetic rubbers such as polymersand copolymers of isobutylene, ethylene, styrene and their homologues,polyvinyl chloride, polyvinyl ether, polyvinyl acetate, polyvinylalcohols, polyacrylic nitriles, polyacrylic esters, polyacrylic amides,polyurethanes, polymers of adipic acid and their derivatives;isocyanates, polyesters, terepthalic acid reins, halogenated plastics,especially those containing fluorine; phenol, cresol and othercondensation resins, silicone resins and rubbers; animal, vegetable andsynthetic glues; inorganic bonding agents such as water glass and thelike, or mixtures or copolymerizates of these substances.

All these bonding materials may be used in various forms, as liquids, inplastic form, as solutions, emulsions, latices and suspensions. In theseforms the agents are applied to the fibers, if necessary, together witha coag ulant, such as an acid, a salt with an acid reaction or any otherelectrolyte. f a rubber latex is used together with asbestos, nocoagulants are in general required.

The solid substances can be applied in various ways to the fibers, suchas by dipping the fibers, which then must not yet have been spun intoyarns, into a solution or dispersion of a bonding agent, or by stirringor scattering the loose fibers into a dispersion or a solution of theagent together With the solid lubricant. The entire mixture is thenthoroughly worked, and the bonding agent is precipitated on the fiber bycoagulation together with the solid lubricant; the substance is thendried, unravelled and spun in the usual manner.

The primary material for the production of the yarn can also be obtainedby brushing or spraying such a liquid or solution on the dried fibrousmaterial not later than when on the card, after which the solidlubricants are applied, or by immersing, brushing or spraying onmixtures ofthe solutions containing the bonding agent or dispenrsionswith the finely dstributed solid lubricants. In each case the solids areapplied either after the individual fibers have been coated with thebonding a ents,

or the solids and the bonding agents are applied together. If the solidsare applied after the bonding agents they may either be sprayed on orapplied electrostatically.

After each single fiber has been coated with the solids as describedabove and preferably also with the bonding agents, they are spun intoyarn in the usual manner.

If the solid lubricants adhere to the fibers by themselves the use ofbonding agents is not necessary.

For another method of the production of such yarns the individual fibersand the lubricating solids, preferably together with the bonding agents,are mixed together to form a pulp such as is used in the manufacture ofpaper. This pulp is then processed so as to give paperlike sheets orfleeces, which are then cut into narrow strips and twisted together(similar to paper string) so that yarn-like threads are obtained whichare then treated in the same way as described above to form packings.

This subsequent treatment can be carried out in a variety of ways:either by producing reels having layers of yarn windings, wherein thewindings of each layer are crossed with the windings of the precedinglayer to make them strong enough; or, as in the manufacture of textiles,by producing woven, knitted or plaited fabrics having a width roughlyequal to the axial length of the packing required which are then rolledup to give the packings required. Alternatively, wider fabrics can bemade which are then cut up into widths of the required size.

The threads can also be plaited or laced around a former to a suflicientthickness to obtain a packing.

It is also possible to wind a long thread of the type described abovearound the metal former to be packed, thus building up the packing atthe point at which it is required.

These and other objects of this invention will bea come more apparentupon consideration of the following description taken together with thefollowing drawings diagrammatically showing some of the packingembodiments and in which:

FIGURE 1 is a flow chart of one mode of this invention.

FIGURES 2 and 3 show a packing wound of individual layers of yarn toform a coil, in section and in plan with parts thereof cut away;

FIGURE 4 shows a packing produced by rolling up a woven or knittedfabric;

FIGURE 5 shows how the material can be plaited around a former toprovide a packing, and

FIGURE 6 shows how a single long thread of the the type described aboveis wound around a shaft in order to produce a packing where it isrequired.

In FIGURES 2 and 3 the packing is built up of a number of layers 1 and 2of yarns; the direction of the threads 3 and 4 of two adjacent layers ofyarn are opposite such that the threads cross each other thereby givingthe reel greater strength. In FIGURE 4, woven or knitted fabric 6 isrolled on a former forming a packing 5. In FIGURE 5, a thread 8 orslightly wider braids made from such threads are plaited to form afabric which is then wound onto the former 15. The reel 7 so produced isthen removed from the former and can be used as packing. FIGURE 6 showshow a long thread 9 is wound on a shaft 10 whose diameter at 12 isslightly larger than at 13. Winding of the thread commences at theshoulder 11 and is continued until the diameter of the reel isapproximately the same as that of the shaft at 12.

This characteristic of the invention of enveloping practically allfibers individually with the solid lubricant enables a large quantity ofthe later to be introduced into the stuffing box packing. Withconventional methods, in which yarns, fabrics or foils were coated withlubricating additives only on the outside, eg with graphite, not morethan to by volume of these solid additives could be incorporated intothe stuffing box packing; with the present method, on the other hand, upto by volume can be incorporated into the packing in such a manner thatthese lubricating solids are uniformly distributed over the entire crosssection of the packing. As a result the packing contains a very highproportion of these solid lubricants which are not so easily washed orworn out.

Many of these solid lubricants are in the form of small flakes with acharacteristic crystal latice associated with a particularly lowcoefiicient of friction. Other additives, such as lead, aluminium orcopper in powder form are mostly so soft that they very soon assume thisshape of small flakes in operation, thereby again providing very goodfriction characteristics.

The packings can also be treated with certain chemicals if particularproperties are required, eg to improve the resistance against very coldor very hot fluids such as ordinary water, boiler feed water, or seawater; against acids, lyes, salt solutions; against inorganic andorganic solvents and their mixtures, oils and gases; against foodstuffs, medicines etc. Particularly suitable for use as such additivesare silicones and synthetic oils and rubbers containing fluorine, but ingeneral any of the substances mentioned above as bonding agents can beused for this purpose. These and other substances can either beincorporated with the fibers or they can be applied to the packings inthe form of solutions, melts, emulsions or suspensions. In the same wayfats can be added to the yarn or the packings, or the packings can befat impregnated in the known manner.

Example I Spun fibers made of asbestos or other fibrous raw material areprocessed in a quantity of about 60%, with 35% powdered graphite and 5%natural rubber latex (measured dry) in a pulp engine in the usual papermaking manner, i.e. with about 50 times as much water added; the fiberswill then be enveloped with the graphite. The actual amount of water maydiffer according to the condition of the fibers. Basically the amount ofwater shall be about 10 to times the amount of solids and shall increaseas the proportion of fibers in the mixture increases.

In order to improve the adhesion of the graphite to the fibers the latexcan be coagulated by the addition of a trace of acid. The mixture isthen made into paper-like foils on the endless wire or the boardmachine; after drying these are cut up into fibers by means of adeviling machnie or similar appliance. This gives individual fibers eachof which is completely enclosed in graphite.

These fibers which are completely enclosed in graphite are thenprocessed in the manner usually in the textile industry to be made intothreads. First they are oriented on the card in the usual manner toobtain a roving, then they are spun by being rotated on a spinningmachine and finally doubled on a twining machine. The threads soproduced are completely saturated with graphite and can be made intostufiing box packings by plaiting on a plaiting or lacing machine or byweaving, knitting and final process of the woven, knitted or plaitedfabrics in the usual manner.

Example 2 10 parts of cotton fibers are mixed with a suspensioncontaining 87 parts of graphite and such an amount of a 20% solution ofacrylonitrile in dimethyl formamide that the dry components ofacrylonitrile weigh about 3 parts. Inorder to achieve proper mixing thesuspension consisting of the graphite and the acrylonitrile solution isadded to the fibers while the latter are moving over heated surfaces.This will evaporate the solvent leaving individual fibers completelyenclosed in graphite which are then processed in the manner usual in thetextile industry as described in Example 1. The ratio of (cottonfibers-i-bonding agent): graphite is about 23:77 by volume.

Example 3 Abestos spining fibers are processed in the usual manner on acard or a double card. The corresponding lap is treated with a graphitesuspension consisting of 95 parts by weight of graphite and 100 parts byweight of a 5% neoprene latex in such manner that all fibers arecompletely enclosed in graphite which requires a ratio of about 80 partsby volume of graphite to 20 parts by volume of asbestos and bondingagent. Then the dispersion agent is removed by heating, and the graphitefiber lap is processed in the usual manner to give a roving which ismade into a packing by weaving, knitting, plaiting or just by winding iton a mandrel or a shaft.

Example 4 Loose asbestos spinning fibers are sprayed with a solution ofnitrocellulose in amyl acetate such that the quantity ratio of asbestosto solvent-free nitrocellulose solution is 98:2. Then a mixture ofapproximately equal parts of talc and mica is applied according to anelectrostatic flaking method in such a manner that every single fiber iscompletely enclosed; this must be done as soon as possible after thenitrocellulose solution has been applied so that the fibers are stillsticky. In this manner such a quantity of the talc-mica mixture isapplied as will produce a ratio of 70 parts by volume of talc and micato 30 parts by volume of fibers and bonding agent.

Example 5 8 parts by weight of cellulose staple fibers about 30 to 80millimeters long are suspended in water in a pulp machine in the usualmanner, and 90 parts by Weight of natural graphite containing 98 to 99%of carbon are added. The amount of water should be about 20 to 50 timesthe amount of fibers. Then a quantity of natural rubber latexcorresponding approximately to two parts of the dry substance is added,and finally a coagulant, e.g. a weak acid or alum. These chemicalsprecipitate the rubber and the graphite onto the fibers in such a waythat the mixture can be processed to give a homogeneous fiber fleece.After it has been dried this fleece is cut up in a deviling machine; thefibers are then made into a sliver on the card and finally into a yarnon a spinning machine. A woven or knitted fabric can be produced fromsuch yarns which can be turned into stutling box packings. In thesepackings the ratio by volume of (fibers and bonding agent) to graphiteis about 15 to 85.

Example 6 Into a solution of 3 parts of polyvinyl acetate (referred toas the dry material) in amyl acetate are stirred one after the other thefollowing: 10 parts of molybdenum disulphide, 75 parts of fine lead dustand parts of chrysotyl asbestos fibers.

The substance is dried by evaporating the solvent. Any large lumps whichmay have formed are cut up in a deviling machine; the material is thenprocessed so that the fibers are made into a sliver in the same manneras given in Example 5. The ratio by volume is about 54 parts of fibersand bonding agent to 46 parts of lead and molybdenum disulphide.

It is understood that the methods described above for enclosing theindividual fibers in solid substances, applying the bonding agents andsolids, processing of the individual fibers to give yarns and processingthe yarns to give finished packings are only mentioned here as examplesof the present invention but are not intended to limit the scope of theinvention in any way. The amount of protection for the invention is tobe described by the following claims.

I claim:

1. In a process for producing stuffing box packings made up of orientedfibers formed into yarns and solids having lubricating properties onsaid fibers, the steps which comprise preparing a mixture includingstaple fibers and lubricating solids in small flake form, the Volume ofthe solids being at least 30% of the fibers and solids combined, forminga paper-like foil of the mixture and drying the foil, deviling the foilto form individual fibers, subsequently carding the fibers to form asliver, intertwining the sliver into a yarn and forming the packing fromsaid yarn in a suitable manner, whereby every individual fiber issubstantially completely enveloped by the solids.

2. The process of claim 1 wherein an adhesive binding agent is added inthe step of preparing the mixture.

3. The process of claim 1 wherein the staple fibers are asbestos fibers.

4. The process of claim 1 wherein the staple fibers are cot-ton fibers.

5. The process of claim 1 wherein the staple fibers are cellulose staplefibers.

6. The process of claim 1 wherein the staple fibers are glass fibers.

7. The process of claim 1 wherein the staple fibers are mineral woolfibers.

References (Jilted in the file of this patent UNITED STATES PATENTS267,537 Johns Nov. 14, 1882 862,899 Garlock Aug. 13, 1907 926,996 MorrisJuly 6, 1909' 951,827 Miller Mar. 15, 1910 1,256,881 Deventer Feb. 19,1918 1,608,165 Brown et al. Nov. 23,1926 1,982,381 Hayes-Gratze Nov. 27,1934 2,099,242 Stewart Nov. 16, 1937 2,134,324 Brackett Oct. 25, 19382,210,004 Rautenstrauch Aug. 6, 1940 2,301,998 Berstein et al. Nov. 17,1942 2,404,952 Fiechter July 30, 1946 2,667,684 Boyer et a1. Feb. 2,1954 2,743,511 Genovese May 1, 1956

1. IN A PROCESS FOR PRODUCING STUFFING BOX PACKINGS MADE UP OF ORIENTEDFIBERS FORMED INTO YARNS AND SOLIDS HAVING LUBRICATING PROPERTIES ONSAID FIBERS, THE STEPS WHICH COMPRISE PREPARING A MIXTURE INCLUDINGSTAPLE FIBERS AND LUBRICATING SOLIDS IN SMALL FLAKE FROM, THE VOLUME OFTHE SOLIDS BEING AT LEAST 30% OF THE FIBERS AND SOLIDS COMBINED, FORMINGA PAPER-LIKE FOIL OF THE MIXTURE AND DRYING THE FOIL, DEVILING THE FOILTO FORM INDIVIDUAL FIBERS, SUBSEQUENTLY CARDING THE FIBERS TO FORM ASILVER, INTERTWINING THE SILVER INTO A YARN AND FORMING THE PACKING FROMSAID YARN IN SUITABLE MANNER, WHEREBY EVERY INDIVIDUAL FIBER ISSUBSTNATIALLY COMPLETELY ENVELOPED BY THE SOLIDS.